This study was divided into 2 sequential phases. The Screening/Eligibility Phase included one Screening Visit and two Eligibility Visits, during which subjects washed out of all other intraocular pressure (IOP)-lowering medications and dosed with TRAVATAN Z®, XALATAN®, or LUMIGAN®, 1 drop instilled in each eye once daily for 28 days. Subjects who met all inclusion/exclusion criteria were randomized at the second Eligibility Visit. The Treatment Phase consisted of two on-therapy visits (Week 2 and Week 6).